function show_runtime() {
  window.setTimeout("show_runtime()", 1000);
  X = new Date("01/08/2020 00:30:00");
  Y = new Date();
  T = (Y.getTime() - X.getTime());
  M = 24 * 60 * 60 * 1000;
  a = T / M;
  A = Math.floor(a);
  b = (a - A) * 24;
  B = Math.floor(b);
  c = (b - B) * 60;
  C = Math.floor((b - B) * 60);
  D = Math.floor((c - C) * 60);
  runtime_span.innerHTML = "本站已运行: " + A + "天" + B + "小时" + C + "分" + D + "秒"
}
show_runtime();

function getRTime() {
  var EndTime = new Date('2021/02/12 00:00:00'); //截止时间
  var NowTime = new Date();
  var t = EndTime.getTime() - NowTime.getTime();
  var d = Math.floor(t / 1000 / 60 / 60 / 24);
  var h = Math.floor(t / 1000 / 60 / 60 % 24);
  var m = Math.floor(t / 1000 / 60 % 60);
  var s = Math.floor(t / 1000 % 60);

  document.getElementById("t_d").innerHTML = d + " 天";
  document.getElementById("t_h").innerHTML = h + " 时";
  document.getElementById("t_m").innerHTML = m + " 分";
  document.getElementById("t_s").innerHTML = s + " 秒";
}
setInterval(getRTime, 1000);